A mass trauma situation, which turns out to be a ferryboat accident, challenges the whole staff of Seattle Grace Hospital. Richard finds difficulty in coping with his separation from his wife and dyes his hair "for the ladies", which becomes an internal joke between Mark, Burke and Derek. Cristina tries to tell Meredith about her upcoming marriage, but doesn't have the strength to. George promises to find a woman's son, who has been separated from her at the accident. The woman refuses to go into surgery until she is assured that her son is alive. Izzie has to take care of a man who got stuck between two cars on the ferry, but nobody helps her due to the large number of injured people. Alex rescues a pregnant woman with severe wounds on her face, and promises to take care of her. Meredith looks after a girl who has been separated from her mother after the accident, but accidentally falls into the water and drowns, with nobody but the little girl as a witness.

Meredith is still underwater, but nobody seems to notice. Her worsening condition makes her rescuing an urgent matter. Derek finds her coat on a man she had helped, and starts looking for her and, much to his shock, the little girl Meredith took care of suggests that she is in the water. Derek saves her, but she is almost dead, due to hypothermia. Izzie has to perform brain surgery on a man stuck between cars, as he begins to experience seizures. She drills holes into his head, perforates his skull and ultimately saves his life before he is rescued and transferred to Seattle Grace Hospital. George lies to the woman whose son he had been looking for, in order to get to surgery, but still doesn't have any luck in locating him. Alex finds no hope in searching for the pregnant Jane Doe's family as she undergoes surgery. The interns find out about Meredith's situation and express their hopelessness. She wakes up in what appears to be limbo and meets her deceased acquaintances.